Line Segment Detection for Register Marks
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Solution Overview
Problem
Conventional line segment detection methods in cutting plotters are prone to errors due to foreign substances and surface undulations on the cutting target medium, leading to incorrect detection of register marks.
Innovation Solution
A line segment detection apparatus and control program that uses a sensor to detect changes in light reflection while moving in two-dimensional directions, employing a processing unit to differentiate between regions of varying reflectance and determine line segments based on signal changes in both directions, thereby distinguishing register marks from foreign substances and surface irregularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If line segment detection is performed based on light reflection difference between background and register mark, then detection function is achieved, but detection accuracy deteriorates due to foreign substances and surface undulations
Solution Approach 1:
The patent transitions from one-dimensional detection (single direction scanning) to two-dimensional detection by scanning in both first and second directions. The processing unit determines line segments by analyzing signal changes in multiple directions, which allows differentiation between actual register marks and false detections caused by foreign substances or surface undulations that appear in only one direction.
Solution Approach 2:
The detection process is segmented into multiple independent scanning operations in different directions. The processing unit separately analyzes signal changes in the first direction and second direction, then integrates these results to make final determination. This segmentation allows systematic elimination of false positives by cross-validating detections across multiple directional scans.
2Measurement precision
If single-direction scanning is used for line segment detection, then detection speed is maintained, but detection precision deteriorates due to inability to distinguish register marks from false signals
Solution Approach 1:
The patent adds a second scanning dimension without fundamentally redesigning the hardware. The same photosensor and driving unit are reused, simply adding another scanning direction. This dimensional expansion improves precision by providing multi-directional verification while avoiding the complexity of adding separate detection systems.
Solution Approach 2:
The existing photosensor and driving unit perform multiple functions: they scan in the first direction to detect potential line segments, then scan in the second direction to verify these detections. This multi-functionality of the same hardware components allows improved precision without proportionally increasing device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Accurately detects line segments constituting register marks without being influenced by foreign substances or the state of the cutting target medium, enhancing the reliability of cutting plotter operations.
Implementation Method 1
a sensor (16) configured to detect light reflected by a surface of a cutting target medium (2)
Data Source
AI summary
A line segment detection apparatus includes a head that supports a sensor configured to detect light reflected by a surface of a cutting target medium, a driving unit configured to move the head in two-dimensional directions relatively to the medium, and a processing unit configured to drive the driving unit and perform arithmetic processing on an output of the sensor. The processing unit includes a region detection unit configured to detect a region different in reflectance from surroundings based on a change of a signal output from the sensor when the sensor was moved in a first direction, and a determination unit configured to determine whether the region is a line segment, based on the change of the signal output from the sensor when the sensor passed a point in the region and was moved in a second direction perpendicular to the first direction.